US5611928A - Process for treating waste water - Google Patents
Process for treating waste water Download PDFInfo
- Publication number
- US5611928A US5611928A US08/454,316 US45431695A US5611928A US 5611928 A US5611928 A US 5611928A US 45431695 A US45431695 A US 45431695A US 5611928 A US5611928 A US 5611928A
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- waste water
- hydrogen peroxide
- salt
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- 239000002351 wastewater Substances 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 31
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 52
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical class [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 10
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical group [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 23
- 239000011790 ferrous sulphate Substances 0.000 claims description 16
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 16
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 16
- 239000010802 sludge Substances 0.000 claims description 12
- 150000003839 salts Chemical class 0.000 claims description 6
- 239000000126 substance Substances 0.000 description 17
- 238000001556 precipitation Methods 0.000 description 16
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 14
- 239000001301 oxygen Substances 0.000 description 14
- 229910052760 oxygen Inorganic materials 0.000 description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 12
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 229910052698 phosphorus Inorganic materials 0.000 description 8
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 6
- 239000011574 phosphorus Substances 0.000 description 6
- 239000005416 organic matter Substances 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 150000004045 organic chlorine compounds Chemical class 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000013256 coordination polymer Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 2
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 235000015097 nutrients Nutrition 0.000 description 2
- 150000002896 organic halogen compounds Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- VGVRPFIJEJYOFN-UHFFFAOYSA-N 2,3,4,6-tetrachlorophenol Chemical class OC1=C(Cl)C=C(Cl)C(Cl)=C1Cl VGVRPFIJEJYOFN-UHFFFAOYSA-N 0.000 description 1
- ISPYQTSUDJAMAB-UHFFFAOYSA-N 2-chlorophenol Chemical compound OC1=CC=CC=C1Cl ISPYQTSUDJAMAB-UHFFFAOYSA-N 0.000 description 1
- 235000018185 Betula X alpestris Nutrition 0.000 description 1
- 235000018212 Betula X uliginosa Nutrition 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000031018 biological processes and functions Effects 0.000 description 1
- 238000004061 bleaching Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000009388 chemical precipitation Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000000701 coagulant Substances 0.000 description 1
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 229920000867 polyelectrolyte Polymers 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1205—Particular type of activated sludge processes
- C02F3/1215—Combinations of activated sludge treatment with precipitation, flocculation, coagulation and separation of phosphates
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S210/00—Liquid purification or separation
- Y10S210/928—Paper mill waste, e.g. white water, black liquor treated
Definitions
- the invention relates to a process for treating waste water produced in the forest industry, in which process the waste water is further treated with chemicals after a biological treatment.
- the waste waters of the forest industry contain varying amounts of dissolved and solid organic and inorganic substances derived from the raw materials used.
- the waste waters thus pollute the watercourses into which they are discharged.
- Solid insoluble substances make the water turbid and form a layer of sludge on the floor of the watercourse.
- Organic substances regardless of whether they are dissolved or solid, consume oxygen from the water and directly or indirectly give it a taste or odor.
- a process based on oxidation for the treatment of waste waters is also otherwise known.
- the oxidation of waste water is carried out by using hydrogen peroxide, the oxidative action of which can be enhanced by means of a catalyst, for example, a metal ion, UV light, or ozone.
- the present invention relates to a process for the treatment of the waste waters of the forest industry, enabling the stricter licence conditions to be fulfilled.
- the process provides an efficient method of eliminating the environmental load of both matter causing biological oxygen demand and matter causing chemical oxygen demand, as well as phosphorus, nitrogen and organic halogen compounds.
- waste waters from the forest industry are first treated biologically.
- the waste waters of pulp and paper mills are directed to a biological treatment plant, for example to an activated sludge plant or an aerated pond, in which a large proportion of the small-molecular organic matter can be removed.
- the biologically treated waste water is then precipitated by means of a ferrous salt (Fe 2+ ) and hydrogen peroxide, by adding the chemicals simultaneously or almost simultaneously to the waste water.
- the ferrous salt and the hydrogen peroxide are added either simultaneously or by adding the ferrous salt first and the hydrogen peroxide immediately thereafter.
- the pH must be adjusted by means of a mineral acid, for example sulfuric acid. It is also advisable to adjust the pH before the adding of the ferrous salt.
- the pH range of the system may be 3.5-6. The optimum pH is within the range 3.7-4.2.
- the ferrous salt is preferably ferrous sulfate.
- the amount of ferrous sulfate to be added depends on the type of the waste water.
- the hydrogen peroxide used may have a concentration of 30-50%.
- the weight ratio of the ferrous salt to the hydrogen peroxide may vary within 1:0.01-1:0.3, preferably 1:0.1-1:0.2.
- the precipitate which contains impurities may be separated either by settling or by flotation with or without a polyelectrolyte.
- COD Cr stands for chemical oxygen demand measured by the dichromate method
- BOD 7 stands for biological oxygen demand within seven days, and AOX stands for organic chlorine compounds.
- Table 1 shows results of the precipitation of biologically treated waste water of a pulp mill with ferrous sulfate and hydrogen peroxide.
- Unclarified pulp and paper mill waste water which had been treated biologically and been aerated in the pond (Table 4) was precipitated in the laboratory by adding ferrous sulfate and hydrogen peroxide to the waste water. Reference precipitation was carried out by using a metal salt (ferric sulfate). The pH of the waste water after all the additions of chemicals was 3.8. The weight ratio of ferrous sulfate to hydrogen peroxide was 1:0.05. The formed precipitate was separated by settling, and the clarified water was analyzed for turbidity, COD Cr , BOD 7 , P, N, AOX, and CP (chlorophenol).
- Biologically treated pulp and paper mill waste water which had been aerated in the pond and clarified (Table 5) was precipitated in the laboratory by adding ferrous sulfate and hydrogen peroxide to the waste water. Reference precipitation was carried out by using a metal salt (ferric sulfate). The pH of the waste water after the addition of all the chemicals was 3.8. The weight ratio of ferrous sulfate to hydrogen peroxide was 1:0.05. The formed precipitate was separated by settling, and the clarified water was analyzed for turbidity, COD Cr , P, N, and AOX.
- Waste water flowing into and waste water flowing out of the activated sludge plant of a sulfate pulp mill were treated with ferrous sulfate and hydrogen peroxide.
- the ratios of the ferrous sulfate amounts to the hydrogen peroxide amounts were a) 1:0.10 and b) 1:0.20.
- the results in Table 6 show that the process is more effective in removing organic matter from biologically treated than from untreated waste water.
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Biodiversity & Conservation Biology (AREA)
- Analytical Chemistry (AREA)
- Microbiology (AREA)
- Inorganic Chemistry (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
- Physical Water Treatments (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
- Removal Of Specific Substances (AREA)
- Treatment Of Sludge (AREA)
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
Abstract
PCT No. PCT/FI93/00524 Sec. 371 Date Jul. 14, 1995 Sec. 102(e) Date Jul. 14, 1995 PCT Filed Dec. 3, 1993 PCT Pub. No. WO94/13591 PCT Pub. Date Jun. 23, 1994The invention relates to a process for the treatment of waste waters of the forest industry. According to the invention, waste water is pre-treated biologically, whereafter the further treatment is carried out by using Fe(II) salt and hydrogen peroxide.
Description
The invention relates to a process for treating waste water produced in the forest industry, in which process the waste water is further treated with chemicals after a biological treatment.
The waste waters of the forest industry contain varying amounts of dissolved and solid organic and inorganic substances derived from the raw materials used. The waste waters thus pollute the watercourses into which they are discharged. Solid insoluble substances make the water turbid and form a layer of sludge on the floor of the watercourse. Organic substances, regardless of whether they are dissolved or solid, consume oxygen from the water and directly or indirectly give it a taste or odor.
In spite of the fact that in the past 10-20 years the production of pulp has multiplied in Finland, the waste water load caused by the forest industry has been substantially reduced. The solution to the problem of waste water has, especially in Finland, been the activated sludge process, in which the organic substance is decomposed by micro-organisms. By the activated sludge process, as well as by other biological processes, it is possible to remove from waste water primarily small-molecular organic matter which causes biological oxygen demand (BOD).
The licence conditions set by the authorities presuppose, for reasons of environmental protection, also the removal of solids from waste waters. Solids have indeed been removed by using combinations of biological and chemical processes.
When the activated sludge process is used, the reduction of matter causing chemical oxygen demand (COD), as well as of nutrients such as phosphorus and nitrogen, remains considerably lower than the reduction of matter causing biological oxygen demand. Nutrients are derived not only from waste waters themselves but also from the chemicals possibly added at the biological treatment stage.
It is known to remove large-molecular organic matter (COD) and phosphorus from waste waters by means of chemical precipitation, for example by using aluminum or iron coagulants.
DE application publication 2 521 893 (SCA Development AB) proposes the removal of color and the matter which causes chemical oxygen demand (COD), present in the waste waters from pulp production, especially in waste liquors, by means of hydrogen peroxide and a ferrous salt. However, a satisfactory removal of the matter causing biological oxygen demand is generally not achieved by the use this method.
A process based on oxidation for the treatment of waste waters is also otherwise known. The oxidation of waste water is carried out by using hydrogen peroxide, the oxidative action of which can be enhanced by means of a catalyst, for example, a metal ion, UV light, or ozone.
The latest licence conditions for the waste waters of the forest industry set high requirements on emissions; not only the removal of matter causing chemical oxygen demand (COD) and of phosphorus but also the removal of organic chlorine compounds (AOX) is required. Organic chlorine compounds are formed in connection with bleaching with chlorine chemicals. Since nitrogen, in the form of both organic and inorganic, dissolved, insoluble and colloidal compounds, is also present in the waste waters, the reduction of nitrogen emissions has been set as an objective in licence conditions.
The present invention relates to a process for the treatment of the waste waters of the forest industry, enabling the stricter licence conditions to be fulfilled. The process provides an efficient method of eliminating the environmental load of both matter causing biological oxygen demand and matter causing chemical oxygen demand, as well as phosphorus, nitrogen and organic halogen compounds.
By the process according to the invention, strict licence conditions can be fulfilled in a simple manner by combining a biological treatment process and a process in which chemicals can be used which in themselves will not cause further environmental problems.
The characteristics of the process according to the invention are given in the accompanying patent claims.
In the process according to the present invention, waste waters from the forest industry are first treated biologically. The waste waters of pulp and paper mills are directed to a biological treatment plant, for example to an activated sludge plant or an aerated pond, in which a large proportion of the small-molecular organic matter can be removed. The biologically treated waste water is then precipitated by means of a ferrous salt (Fe2+) and hydrogen peroxide, by adding the chemicals simultaneously or almost simultaneously to the waste water.
The ferrous salt and the hydrogen peroxide are added either simultaneously or by adding the ferrous salt first and the hydrogen peroxide immediately thereafter. Before the adding of the hydrogen peroxide, the pH must be adjusted by means of a mineral acid, for example sulfuric acid. It is also advisable to adjust the pH before the adding of the ferrous salt. The pH range of the system may be 3.5-6. The optimum pH is within the range 3.7-4.2.
The ferrous salt is preferably ferrous sulfate. The amount of ferrous sulfate to be added depends on the type of the waste water. The hydrogen peroxide used may have a concentration of 30-50%.
The weight ratio of the ferrous salt to the hydrogen peroxide may vary within 1:0.01-1:0.3, preferably 1:0.1-1:0.2.
The precipitate which contains impurities may be separated either by settling or by flotation with or without a polyelectrolyte.
By the process according to the invention, in particular the amounts of nitrogen, organic halogen compounds, phosphorus and chlorophenols can be reduced significantly as compared with the processes currently used.
The invention is described in greater detail in the following non-limiting examples and with the help of test results obtained. In these examples
CODCr stands for chemical oxygen demand measured by the dichromate method,
BOD7 stands for biological oxygen demand within seven days, and AOX stands for organic chlorine compounds.
Table 1 shows results of the precipitation of biologically treated waste water of a pulp mill with ferrous sulfate and hydrogen peroxide.
TABLE 1
______________________________________
Precipitation, with ferrous sulfate and hydrogen peroxide,
of waste water taken from the overflow of the activated
sludge plant of a pulp mill. Fe was added in the
experiment at a rate of 160 mg/l waste water.
Before After
precipitation
precipitation
Reduction
mg/l mg/l %
______________________________________
BOD.sub.7 13 3.3 75
COD.sub.Cr
730 100 86
AOX 20.1 2.5 88
N 2.87 0.44 85
P 1.04 0.04 96
Color number
2180 40 98
______________________________________
As can be observed from Table 1, a very good reduction of all of the parameters causing an environmental load is achieved by the process.
TABLE 2
______________________________________
Reduction (%) of COD, AOX, nitrogen (N), and
phosphorus (P) in the total waste water of a pulp plant in
precipitation with ferrous sulfate and hydrogen, before and after
the activated sludge plant (ASP).
Ferrous COD.sub.Cr
AOX N P
Waste kg/kg reduction
reduction
reduction
reduction
water COD.sub.Cr
% % % %
______________________________________
Birch 2.5 64 66 95 96
before ASP
Birch 1.7 61 64 92 92
before ASP
Birch 1.5 85 84 85 97
after ASP
Birch 1.1 72 70 69 96
after ASP
______________________________________
As can be seen from Table 2, the consumption of, for example, ferrous sulfate is substantially higher and the purification result poorer with waste water which has not been treated biologically than with waste water which has been treated biologically.
It is especially advantageous to carry out the ferrous sulfatehydrogen peroxide precipitation on waste water from which small-molecular compounds which decompose easily have been removed, since these compounds otherwise increase the consumption of the precipitation chemicals and, nevertheless, are not precipitated. This is evident from Table 2, showing the results of precipitation of waste water before and after the activated sludge plant.
When ferrous sulfate and hydrogen peroxide were added to waste water which has been treated in the sludge pond of a cardboard mill and does not contain dissolved oxygen (anaerobic state), precipitation does not occur. However, precipitation can be achieved by aeration, i.e. by dissolving oxygen from air into the waste water before the adding of ferrous sulfate and hydrogen peroxide. Table 3 shows the results of precipitation experiments conducted in a laboratory.
TABLE 3
______________________________________
Fe.sup.2+ H.sub.2 O.sub.2
COD.sub.Cr
N P Reduction %
mg/l mg/l mg/l mg/l mg/l COD N P
______________________________________
Original
-- -- 750 3.81 0.49 -- -- --
waste
water
Anaerobic
105 45 no precipitation occurs
Anaerobic
105 60 no precipitation occurs
Aerated 105 45 290 1.46 0.02 61 62 96
______________________________________
As can be seen from Table 3, when the waste water is anaerobic, no precipitation occurs even with a larger dose of hydrogen peroxide. In the oxidation reaction of ferrous iron and organic matter, soluble oxygen also serves as an oxidant.
Unclarified pulp and paper mill waste water which had been treated biologically and been aerated in the pond (Table 4) was precipitated in the laboratory by adding ferrous sulfate and hydrogen peroxide to the waste water. Reference precipitation was carried out by using a metal salt (ferric sulfate). The pH of the waste water after all the additions of chemicals was 3.8. The weight ratio of ferrous sulfate to hydrogen peroxide was 1:0.05. The formed precipitate was separated by settling, and the clarified water was analyzed for turbidity, CODCr, BOD7, P, N, AOX, and CP (chlorophenol).
TABLE 4
______________________________________
Results for unclarified waste water
Reduction %
Property Initial level
FS + H.sub.2 O.sub.2
Metal salt
______________________________________
Turbidity
116 NTU 97 75
COD.sub.CR
550 mg/l 78 68
BOD.sub.7
30 mg/l 83 >83
P.sub.tot
1.3 mg/l 97 84
N.sub.tot
9 mg/l 89 67
AOX 3.03 mg/l 67 36
CP 0.112 mg/l 23 0
______________________________________
Biologically treated pulp and paper mill waste water which had been aerated in the pond and clarified (Table 5) was precipitated in the laboratory by adding ferrous sulfate and hydrogen peroxide to the waste water. Reference precipitation was carried out by using a metal salt (ferric sulfate). The pH of the waste water after the addition of all the chemicals was 3.8. The weight ratio of ferrous sulfate to hydrogen peroxide was 1:0.05. The formed precipitate was separated by settling, and the clarified water was analyzed for turbidity, CODCr, P, N, and AOX.
TABLE 5
______________________________________
Results for clarified waste water
Reduction %
Property Initial level
FS + H.sub.2 O.sub.2
Metal salt
______________________________________
Turbidity
126 NTU 98 97
COD.sub.CR
505 mg/l 92 89
P.sub.tot
1.6 mg/l 94 88
N.sub.tot
8 mg/l 88 50
AOX 2.8 mg/l 83 65
______________________________________
Waste water flowing into and waste water flowing out of the activated sludge plant of a sulfate pulp mill were treated with ferrous sulfate and hydrogen peroxide. The ratios of the ferrous sulfate amounts to the hydrogen peroxide amounts were a) 1:0.10 and b) 1:0.20. The results in Table 6 show that the process is more effective in removing organic matter from biologically treated than from untreated waste water.
TABLE 6
______________________________________
Results before and after the activated sludge plant
Reduction %
Ferrous sulfate
COD.sub.Cr Turbidity
Waste water
mg/mg COD.sub.Cr
a b a b
______________________________________
Before ASP
0.77 3 59 0 96
0.5 62 69 96 93
2.3 64 74 92 92
After ASP 0.86 79 81 90 85
1.7 88 -- 96 --
2.6 91 -- 79 --
______________________________________
Claims (8)
1. A process for treating waste water of at least one of a pulp mill and a paper mill, comprising:
biologically treating the waste water by an activated sludge process; and
chemically treating the biologically treated waste water by adding an Fe(II) salt to the biologically treated waste water and by adding hydrogen peroxide to the biologically treated waste water.
2. The process according to claim 1, wherein the Fe(II) salt is ferrous sulfate.
3. The process according to claim 1 or 2, wherein the weight ratio of the Fe(II) salt to hydrogen peroxide ranges from 1:0.01 to 1:0.3.
4. The process according to claim 3, wherein the weight ratio of Fe(II) salt to hydrogen peroxide is 1:0.1-1:0.2.
5. The process according to claim 1, wherein the biologically treated waste water is adjusted to a pH in the range of 3.5-6 before the adding of the Fe(II) salt and hydrogen peroxide.
6. The process according to claim 5, wherein the biologically treated waste water is adjusted to a pH of 3.7-4.2.
7. The process according to claim 1, wherein the Fe (II) salt and the hydrogen peroxide are added simultaneously.
8. The process according to claim 1, wherein the Fe (II) salt and the hydrogen peroxide are added substantially simultaneously.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI925506 | 1992-12-04 | ||
| FI925506A FI97219C (en) | 1992-12-04 | 1992-12-04 | Waste water purification process |
| PCT/FI1993/000524 WO1994013591A1 (en) | 1992-12-04 | 1993-12-03 | Process for treating waste water |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US5611928A true US5611928A (en) | 1997-03-18 |
Family
ID=8536331
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US08/454,316 Expired - Lifetime US5611928A (en) | 1992-12-04 | 1993-12-03 | Process for treating waste water |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US5611928A (en) |
| EP (1) | EP0672022B1 (en) |
| AT (1) | ATE178291T1 (en) |
| AU (1) | AU5565594A (en) |
| CA (1) | CA2150675C (en) |
| DE (1) | DE69324262T2 (en) |
| ES (1) | ES2130391T3 (en) |
| FI (1) | FI97219C (en) |
| WO (1) | WO1994013591A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6083398A (en) * | 1996-12-02 | 2000-07-04 | Solvay (Societe Anonyme) | Process for the decoloration and detoxification of aqueous effluents |
| WO2004028983A1 (en) * | 2002-09-27 | 2004-04-08 | Shanghai Gi Biotechnology Engineering Co., Ltd. | A method of processing organic wastewater |
| US20110127220A1 (en) * | 2007-12-20 | 2011-06-02 | Otv Sa | Method for Treating Water by Advanced Oxidation and Ballasted Flocculation, and Corresponding Treatment Plant |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI97219C (en) * | 1992-12-04 | 1998-07-14 | Kemira Oy | Waste water purification process |
| US5626717A (en) * | 1995-06-01 | 1997-05-06 | International Paper Company | Oxidative treatment of bleach plant effluent |
| FR2737719B1 (en) * | 1995-08-07 | 1997-10-24 | Burgand Yves | ORGANO-MINERAL PASTE AND USE THEREOF AS A CONSTRUCTION MATERIAL |
| US6569284B1 (en) | 1996-09-24 | 2003-05-27 | International Paper Company | Elemental-chlorine-free bleaching process having an initial Eo or Eop stage |
| WO2011119423A2 (en) | 2010-03-23 | 2011-09-29 | International Paper Company | Improved bctmp filtrate recycling system and method |
| CN101913729B (en) * | 2010-07-20 | 2012-05-23 | 江苏华杉环保科技有限公司 | Denitrification additive for treating urea-containing wastewater and preparation method thereof |
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- 1993-12-03 CA CA002150675A patent/CA2150675C/en not_active Expired - Fee Related
- 1993-12-03 WO PCT/FI1993/000524 patent/WO1994013591A1/en active IP Right Grant
- 1993-12-03 AT AT94900852T patent/ATE178291T1/en active
- 1993-12-03 US US08/454,316 patent/US5611928A/en not_active Expired - Lifetime
- 1993-12-03 DE DE69324262T patent/DE69324262T2/en not_active Expired - Lifetime
- 1993-12-03 EP EP19940900852 patent/EP0672022B1/en not_active Expired - Lifetime
- 1993-12-03 AU AU55655/94A patent/AU5565594A/en not_active Abandoned
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6083398A (en) * | 1996-12-02 | 2000-07-04 | Solvay (Societe Anonyme) | Process for the decoloration and detoxification of aqueous effluents |
| WO2004028983A1 (en) * | 2002-09-27 | 2004-04-08 | Shanghai Gi Biotechnology Engineering Co., Ltd. | A method of processing organic wastewater |
| US20110127220A1 (en) * | 2007-12-20 | 2011-06-02 | Otv Sa | Method for Treating Water by Advanced Oxidation and Ballasted Flocculation, and Corresponding Treatment Plant |
| US8663478B2 (en) * | 2007-12-20 | 2014-03-04 | Veolia Water Solutions & Technologies Support | Method for treating water by advanced oxidation and ballasted flocculation, and corresponding treatment plant |
Also Published As
| Publication number | Publication date |
|---|---|
| FI925506A0 (en) | 1992-12-04 |
| ES2130391T3 (en) | 1999-07-01 |
| AU5565594A (en) | 1994-07-04 |
| FI97219C (en) | 1998-07-14 |
| WO1994013591A1 (en) | 1994-06-23 |
| ATE178291T1 (en) | 1999-04-15 |
| EP0672022B1 (en) | 1999-03-31 |
| FI97219B (en) | 1996-07-31 |
| CA2150675A1 (en) | 1994-06-23 |
| DE69324262D1 (en) | 1999-05-06 |
| DE69324262T2 (en) | 1999-11-11 |
| FI925506L (en) | 1994-06-05 |
| CA2150675C (en) | 2005-05-10 |
| EP0672022A1 (en) | 1995-09-20 |
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